Risk Of Methicillin-resistant Staphylococcus Aureus Infection Research Articles

Barriers to Optimal Surgical Antimicrobial Prophylaxis for Methicillin-Resistant Staphylococcus aureus-Colonized Patients at an Australian Tertiary Teaching Hospital

Background: Surgical antimicrobial prophylaxis (SAP) is a leading indication for antibiotic use in Australian hospitals with established high rates of inappropriate prescribing. Optimal administration of SAP for patients at high risk of methicillin-resistant Staphylococcus aureus (MRSA) infections presents additional complexities. A greater understanding of barriers to optimal SAP in this cohort is required to inform targeted antimicrobial stewardship strategies, optimize SAP, and reduce the rate of surgical site infections (SSIs). Methods: A multiple-choice questionnaire appraising knowledge and barriers to optimal SAP was electronically distributed to key stakeholders. Data from the questionnaire were collated and analyzed using Survey Monkey® (Momentive Inc., San Mateo, CA) data analysis tools. Results: Eighty-three persons provided full or partial responses to the questionnaire. There were 19% of respondents who considered MRSA colonization status of patients to be only "somewhat important" when selecting appropriate SAP. Additionally, 62% of responses did not correctly identify the appropriate SAP regimen for patients who are colonized with MRSA. Several barriers to optimal SAP were identified including poor understanding of SAP guidelines, lack of timely identification of patients confirmed to be colonized with MRSA, inaccurate documentation of antibiotic and surgical start times, and limitations of the current operating room management software program. Conclusions: The high level of engagement from most key stakeholders demonstrates accountability and an overall desire to improve SAP. Barriers identified in this audit should be considered by facilities wishing to optimize compliance with SAP guidelines and consequently reduce SSIs, in particular for patients who are at high risk of MRSA infections.

Reduced pannexin 1-IL-33 axis function in donor livers increases risk of MRSA infection in liver transplant recipients.

Liver transplantation patients are at increased risk for methicillin-resistant Staphylococcus aureus (MRSA) infection, but the molecular mechanism remains unclear. We found that genetic predisposition to low pannexin 1 (PANX1) expression in donor livers was associated with MRSA infection in human liver transplantation recipients. Using Panx1 and Il-33-knockout mice for liver transplantation models with MRSA tail vein injection, we demonstrated that Panx1 deficiency increased MRSA-induced liver injury and animal death. We found that decreased PANX1 expression in the liver led to reduced release of adenosine triphosphate (ATP) from hepatocytes, which further reduced the activation of P2X2, an ATP-activating P2X receptor. Reduced P2X2 function further decreased the NLRP3-mediated release of interleukin-33 (IL-33), reducing hepatic recruitment of macrophages and neutrophils. Administration of mouse IL-33 to Panx1-/- mice significantly (P = 0.011) ameliorated MRSA infection and animal death. Reduced human hepatic IL-33 protein abundance also associated with increased predisposition to MRSA infection. Our findings reveal that genetic predisposition to reduced PANX1 function increases risk for MRSA infection after liver transplantation by decreasing hepatic host innate immune defense, which can be attenuated by IL-33 treatment.

Estimated Methicillin-Resistant Staphylococcus aureus Decolonization in Intensive Care Units Associated With Single-Application Chlorhexidine Gluconate or Mupirocin

Chlorhexidine gluconate (CHG) and mupirocin are widely used to decolonize patients with methicillin-resistant Staphylococcus aureus (MRSA) and reduce risks associated with infection in hospitalized populations. Quantifying the association of an application of CHG alone or in combination with mupirocin with risk of MRSA infection is important for studies evaluating alternative decolonization strategies or schedules and for identifying whether there is room for improved decolonizing agents. To estimate the proportion of patients with MRSA decolonized per application of CHG and mupirocin from existing population-level studies. A stochastic mathematical model of an 18-bed intensive care unit (ICU) in an academic medical center operating over 1 year was used to estimate parameters for the proportion of simulated patients with MRSA decolonized per application of CHG and mupirocin. The model was conducted using approximate bayesian computation with data from an existing meta-analysis of studies conducted from February 2005 through January 2015. Data were analyzed from January 2018 through November 2019. A universal decolonization protocol for colonized patients in the ICU using CHG or CHG and mupirocin in combination was simulated. The proportion of patients with MRSA decolonized per application of CHG and mupirocin was estimated. The estimated proportion of patients with MRSA decolonized per application of CHG was 0.15 (95% credible interval, 0.01-0.42), and the estimated proportion per application of mupirocin in conjunction with CHG was 0.15 (95% credible interval, 0.01-0.54). A lag in colonization detection was associated with decreases in the CHG estimate (0.11; 95% credible interval, 0.01-0.30) and mupirocin estimate (0.10; 95% credible interval, 0.00-0.34), which were sensitive to the value of the modeled contact rate between nurses and patients. A 1% increase in the value of this parameter was associated with a 0.73% increase in the estimated combined outcomes associated with CHG and mupirocin (95% CI: 0.71, 0.75). Gaps longer than 24 hours in the administration of decolonizing agents were associated with a decrease of within-ICU MRSA transmission. Compared with a mean (SD) of 1.23 (0.27) acquisitions per 1000 patient-days in scenarios with no decolonizing bathing, a bathing protocol administering CHG and mupirocin every 120 hours was associated with a mean (SD) acquisition rate of 1.03 (0.24) acquisitions per 1000 patient days, a 16.3% decrease (95% CI, 14.7%-18.0%; P > .001). These findings suggest that there may be room for significant improvement in anti-MRSA disinfectants, including the compounds themselves and their delivery mechanisms. Despite the decolonization estimates found in this study, these agents are associated with robust outcomes after delays in administration, which may help in alleviating concerns over patient comfort and toxic effects.

Identification of Methicillin-Resistant Staphylococcus Aureus From Methicillin-Sensitive Staphylococcus Aureus and Molecular Characterization in Quanzhou, China.

To distinguish Methicillin-Resistant Staphylococcus aureus (MRSA) from Methicillin-Sensitive Staphylococcus aureus (MSSA) in the protein sequences level, test the susceptibility to antibiotic of all Staphylococcus aureus isolates from Quanzhou hospitals, define the virulence factor and molecular characteristics of the MRSA isolates. MRSA and MSSA Pfam protein sequences were used to extract feature vectors of 188D, n-gram and 400D. Weka software was applied to classify the two Staphylococcus aureus and performance effect was evaluated. Antibiotic susceptibility testing of the 81 Staphylococcus aureus was performed by the Mérieux Microbial Analysis Instrument. The 65 MRSA isolates were characterized by Panton-Valentine leukocidin (PVL), X polymorphic region of Protein A (spa), multilocus sequence typing test (MLST), staphylococcus chromosomal cassette mec (SCCmec) typing. After comparing the results of Weka six classifiers, the highest correctly classified rates were 91.94, 70.16, and 62.90% from 188D, n-gram and 400D, respectively. Antimicrobial susceptibility test of the 81 Staphylococcus aureus: Penicillin-resistant rate was 100%. No resistance to teicoplanin, linezolid, and vancomycin. The resistance rate of the MRSA isolates to clindamycin, erythromycin and tetracycline was higher than that of the MSSAs. Among the 65 MRSA isolates, the positive rate of PVL gene was 47.7% (31/65). Seventeen sequence types (STs) were identified among the 65 isolates, and ST59 was the most prevalent. SCCmec type III and IV were observed at 24.6 and 72.3%, respectively. Two isolates did not be typed. Twenty-one spa types were identified, spa t437 (34/65, 52.3%) was the most predominant type. MRSA major clone type of molecular typing was CC59-ST59-spa t437-IV (28/65, 43.1%). Overall, 188D feature vectors can be applied to successfully distinguish MRSA from MSSA. In Quanzhou, the detection rate of PVL virulence factor was high, suggesting a high pathogenic risk of MRSA infection. The cross-infection of CA-MRSA and HA-MRSA was presented, the molecular characteristics were increasingly blurred, HA-MRSA with typical CA-MRSA molecular characteristics has become an important cause of healthcare-related infections. CC59-ST59-spa t437-IV was the main clone type in Quanzhou, which was rare in other parts of mainland China.

Evaluation of the reliability of MRSA screens in patients undergoing universal decolonization.

Colonization of methicillin-resistant Staphylococcus aureus (MRSA) can be detected via nasal screens. Evidence indicates that negative MRSA nasal screens may be used to de-escalate anti-MRSA antibiotics in pulmonary infections. In the ICU, universal decolonization with intranasal mupirocin is implemented to reduce MRSA infection risk. This study aimed to determine whether mupirocin administration affects the reliability of MRSA PCR nasal screens. This retrospective study divided subjects based on timing of intranasal mupirocin administration-before and after MRSA screen. Subjects with confirmed pulmonary infection that received vancomycin, blood/respiratory cultures, and had MRSA PCR screen collected were included. Subjects with concurrent infection requiring vancomycin or MRSA infection in prior 30 days were excluded. Primary outcome of this non-inferiority study was the negative predictive value (NPV) of the screen. Secondary outcomes included the positive predictive value (PPV), sensitivity, and specificity of the screen and duration of vancomycin. Ultimately, 125 subjects were included in each group. The NPV in the group receiving mupirocin before screen was 95.2%, whereas the NPV in the group receiving mupirocin after screen was 99%. The difference between groups was -3.8% (90% CI -7.8%-0.2%; p=0.31), which failed to meet non-inferiority criteria. The secondary outcomes of PPV, sensitivity and specificity of the screen were similar in both groups. The duration of vancomycin was significantly longer in subjects receiving mupirocin before screen (3 days vs. 2 days; p<0.05). Intranasal mupirocin prior to the screen may reduce NPV in pulmonary infections. Approach de-escalation of vancomycin based on screen results with caution.

Evaluating the Use of Ultraviolet Light to Reduce Transmission of Methicillin-resistant Staphylococcus Aureus in Emergency Medical Service Vehicles

<h3>Background</h3> Emergency medical service (EMS) vehicles may pose pathogen exposure risks for patients on route to a healthcare facility. One organism, particularly of concern in this environment, is methicillin-resistant Staphylococcus aureus (MRSA). The objective of this study was to develop a surface transmission model for estimating MRSA infection risk reductions associated with motion-activated ultraviolet (UV-C) light disinfection on surfaces in between hand-to-surface contacts in EMS vehicles. <h3>Methods</h3> A published mathematical transmission model was adapted to estimate MRSA transmission and infection risk for a patient during an emergency call. Two simulated scenarios were explored: 1) Baseline (no UV-C) and 2) UV-C disinfection (intervention) on a heart monitor, keyboard and portable radio in between contacts. The simulation was adapted to estimate the probability of a patient's wound exposure to MRSA and subsequent infection risk during a single transport. Variability and uncertainty in EMS personnel hand-to-medical equipment behavior and in MRSA concentration on high contact surfaces were accounted for within the model using a Monte Carlo simulation approach, where a series of potential outcomes could be considered. <h3>Results</h3> Over a 34-minute period, MRSA concentrations on both patient's wound and paramedics' hands reached a steady state. Baseline infection (no UV-C light) risk was 3.5 × 10-8 on average. The infection risk for the UV-C light disinfection scenario was 2.53 × 10-8 on average. The reduction in mean infection risk was 27.8%. With the UV-C light intervention, there was a decrease in the overall MRSA surface concentrations within the EMS vehicle. <h3>Conclusions</h3> This mathematical simulation demonstrates that UV-C light disinfection within EMS vehicle may reduce MRSA infection risks for patients with when only three surfaces are targeted for treatment. Future studies are planned to better characterize paramedic behaviors that drive surface and hand contamination rates and to evaluate variables of UV-C light efficacy.

Factors Associated with Development of Invasive MRSA Infection in the Neonatal Intensive Care Unit

Purpose Critically ill infants in the neonatal intensive care unit (NICU) are particularly susceptible to methicillin-resistant Staphylococcus aureus (MRSA) colonization secondary to horizontal transmission from colonized family members, healthcare workers, or presence of MRSA on hospital surfaces. MRSA colonization poses risk for subsequent infection, and thus, infants in the NICU are at increased risk of invasive MRSA infection. Methods We conducted a retrospective cohort study of patients admitted to the St. Louis Children’s Hospital (SLCH) NICU from 2009-2017 who were …

Homelessness, Personal Hygiene, and MRSA Nasal Colonization among Persons Who Inject Drugs.

Methicillin-resistant Staphylococcus aureus (MRSA) infection is a leading cause of hospitalization and medical visits among individuals experiencing homelessness and also among persons who inject drugs (PWID), populations with significant overlap in urban centers in the USA. While injection drug use is a risk factor for MRSA skin infections, MRSA is also known to transmit easily in crowded, public locations in which individuals have reduced personal hygiene. Individuals in urban centers who experience homelessness or drug addiction may spend significant amounts of time in environments where MRSA can be easily transmitted, and may also experience reduced access to facilities to maintain personal hygiene. We assessed the relationship between homelessness, personal hygiene, and MRSA nasal colonization, a proxy for MRSA infection risk, in a study of PWID in Boston, MA (n = 78). Sleeping in a homeless shelter for at least one night in the last 3months was significantly associated with MRSA nasal colonization (OR 3.0; p = 0.02; 95% CI 1.2, 7.6). Sleeping at more than one place during the last week (considered a metric of elevated housing instability) was also associated with a threefold increase in odds of MRSA nasal colonization (OR 3.1; p = 0.01; 95% CI 1.3, 7.6). MRSA nasal colonization was strongly associated with use of public showers (OR 13.7; p = 0.02; 95% CI 1.4, 132.8), although few people in this study (4 of 78) reported using these public facilities. Sharing bedding with other people was also associated with increased risk of MRSA colonization (OR 2.2; p = 0.05; 95% CI 1.0-4.7). No associations between hand hygiene, frequency of bathing or clothes laundering, or street sleeping were observed. Use of public facilities supporting persons experiencing homelessness and housing instability, including shelters and public showers, is associated with an increased risk of MRSA nasal colonization in this study. Personal hygiene behaviors appear less associated with MRSA nasal colonization. Environmental assessments of MRSA contamination in homeless shelters and public sanitation facilities are warranted so as to inform appropriate intervention activities.

Decolonization to Reduce Postdischarge Infection Risk among MRSA Carriers

BackgroundHospitalized patients who are colonized with methicillin-resistant Staphylococcus aureus (MRSA) are at high risk for infection after discharge.MethodsWe conducted a multicenter, randomized, controlled trial of postdischarge hygiene education, as compared with education plus decolonization, in patients colonized with MRSA (carriers). Decolonization involved chlorhexidine mouthwash, baths or showers with chlorhexidine, and nasal mupirocin for 5 days twice per month for 6 months. Participants were followed for 1 year. The primary outcome was MRSA infection as defined according to Centers for Disease Control and Prevention (CDC) criteria. Secondary outcomes included MRSA infection determined on the basis of clinical judgment, infection from any cause, and infection-related hospitalization. All analyses were performed with the use of proportional-hazards models in the per-protocol population (all participants who underwent randomization, met the inclusion criteria, and survived beyond the recruitment hospitalization) and as-treated population (participants stratified according to adherence).ResultsIn the per-protocol population, MRSA infection occurred in 98 of 1063 participants (9.2%) in the education group and in 67 of 1058 (6.3%) in the decolonization group; 84.8% of the MRSA infections led to hospitalization. Infection from any cause occurred in 23.7% of the participants in the education group and 19.6% of those in the decolonization group; 85.8% of the infections led to hospitalization. The hazard of MRSA infection was significantly lower in the decolonization group than in the education group (hazard ratio, 0.70; 95% confidence interval [CI], 0.52 to 0.96; P=0.03; number needed to treat to prevent one infection, 30; 95% CI, 18 to 230); this lower hazard led to a lower risk of hospitalization due to MRSA infection (hazard ratio, 0.71; 95% CI, 0.51 to 0.99). The decolonization group had lower likelihoods of clinically judged infection from any cause (hazard ratio, 0.83; 95% CI, 0.70 to 0.99) and infection-related hospitalization (hazard ratio, 0.76; 95% CI, 0.62 to 0.93); treatment effects for secondary outcomes should be interpreted with caution owing to a lack of prespecified adjustment for multiple comparisons. In as-treated analyses, participants in the decolonization group who adhered fully to the regimen had 44% fewer MRSA infections than the education group (hazard ratio, 0.56; 95% CI, 0.36 to 0.86) and had 40% fewer infections from any cause (hazard ratio, 0.60; 95% CI, 0.46 to 0.78). Side effects (all mild) occurred in 4.2% of the participants.ConclusionsPostdischarge MRSA decolonization with chlorhexidine and mupirocin led to a 30% lower risk of MRSA infection than education alone. (Funded by the AHRQ Healthcare-Associated Infections Program and others; ClinicalTrials.gov number, NCT01209234.)

Postdischarge MRSA Decolonization to Prevent Infections

Patients who are carriers of methicillin-resistant Staphylococcus aureus (MRSA) are at increased risk for subsequent MRSA infection after

Chlorhexidine-based body washing for colonization and infection of methicillin-resistant &lt;em&gt;Staphylococcus aureus&lt;/em&gt; and vancomycin-resistant &lt;em&gt;Enterococcus&lt;/em&gt;: an updated meta-analysis

BackgroundThe effects of chlorhexidine-based body washing (CHW) on health care-associated infections have been reported in numerous studies, while their findings remain conflicting. This study aims to update the evidence for the effects of CHW on the risk of colonization or infection with hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE).MethodsTwo independent authors searched PubMed, Embase, and Cochrane Library from inception through February 2018. We selected all observational studies or clinical trials for the effect of CHW on the risk of colonization and infection with hospital-acquired MRSA or VRE. Random-effects models were applied to calculate summary incidence rate ratios (IRRs) for the related associations.ResultsOf 140 records identified, we obtained data from 17 relevant articles for meta-analysis. Compared with patients without antiseptic bathing, patients with CHW had a significantly lower risk of MRSA colonization (IRR 0.61, 95% CI 0.48–0.77) and VRE colonization (IRR 0.58, 95% CI 0.42–0.80). Similarly, we also noted that patients with CHW had a significantly lower risk of MRSA infection (IRR 0.65, 95% CI 0.52–0.81). However, no significantly lower risk of VRE infection (IRR 0.61, 95% CI 0.30–1.25) was noted in patients with CHW. Sensitivity analyses or trim-and-fill method confirmed the robustness of the findings.ConclusionCurrent evidence supports that patients with CHW had a significantly lower risk of MRSA or VRE colonization and a lower risk of MRSA infection. More evidence should be accumulated to reinforce these findings, especially on the effect of CHW on the risk of VRE infection.

Methicillin-resistant Staphylococcus aureus skin and soft tissue infections in young people in custody in New South Wales.

Methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTIs) are problematic for incarcerated adolescents but have not been previously researched. This was a 2-year prospective study of all New South Wales Juvenile Custodial Centres involving incarcerated youth aged 12-20 years. The main outcomes measured were MRSA SSTIs, MRSA molecular subtypes and associations with MRSA infection. Variables included age, gender, SSTI site and type, Indigenous status, incarceration time, lifetime incarcerations, intravenous drug use, overweight/obesity, recent antibiotic use and health centre presentations. From February 2013 to January 2015, there were 77 SSTIs (92.2% male, 59.2% Indigenous, mean age 16.9 years). The majority (77.9%) were collections, mostly on the lower limb (44.2%), and 33 (42.9%) isolates were MRSA; 94% were Panton-Valentine leukocidin positive. This represents 11 SSTIs per 1000 custodial admissions, and 4.7 MRSA SSTIs per 1000 custodial admissions. Independent associations with MRSA SSTI (vs. non-MRSA SSTI) were Indigenous status (adjusted odds ratio (AOR) 5.92, P < 0.001), presenting with a collection (AOR 18.29, P < 0.001) and recent antibiotic use (AOR 3.62, P < 0.05). Incarcerated Australian youth have high rates of MRSA SSTIs, comparable to rates in US adult inmates, but with different molecular subtypes. At particular risk of MRSA infection are Indigenous youth, those with recent antibiotic use and those presenting with a collection. Many MRSA infections present at custodial admission, making surveillance and containment important, along with avoidance of unnecessary antibiotics and hand hygiene. Panton-Valentine leukocidin-positive MRSA predominates and is known for causing flu-associated necrotising pneumonia. Albeit a rare outcome, the seasonal influenza vaccination should be mandatory for youth in custody and custodial staff.

The Role of Negative Methicillin-Resistant Staphylococcus aureus Nasal Surveillance Swabs in Predicting the Need for Empiric Vancomycin Therapy in Intensive Care Unit Patients.

OBJECTIVES The role of methicillin-resistant Staphylococcus aureus (MRSA) nasal surveillance swabs (nasal swabs) in guiding decisions about prescribing vancomycin is unclear. We aimed to determine the likelihood that patients with negative MRSA nasal swabs develop subsequent MRSA infections; to assess avoidable vancomycin days for patients with negative nasal swabs; and to identify risk factors for having a negative nasal swab and developing a MRSA infection during the intensive care unit (ICU) stay. METHODS This retrospective cohort study was conducted in 6 ICUs at a tertiary-care hospital from December 2013 through June 2015. The negative predictive value (NPV), defined as the ability of a negative nasal swab to predict no subsequent MRSA infection, was calculated. Days of vancomycin continued or restarted after 3 days from the collection time of the first negative nasal swab were determined. A matched case-control study identified risk factors for having a negative nasal swab and developing MRSA infection. RESULTS Of 11,441 patients with MRSA-negative nasal swabs, the rate of subsequent MRSA infection was 0.22%. A negative nasal swab had a NPV of 99.4% (95% confidence interval [CI], 99.1%-99.6%). Vancomycin was continued or started after nasal swab results were available in 1,431 patients, translating to 7,364 vancomycin days. No risk factors associated with MRSA infection were identified. CONCLUSIONS In our hospital with a low prevalence of MRSA transmission, a negative MRSA nasal swab was helpful in identifying patients with low risk of MRSA infection in whom empiric vancomycin therapy could be stopped and in whom the subsequent initiation of vancomycin therapy during an ICU admission could be avoided. Infect Control Hosp Epidemiol 2018;39:290-296.

Characterization of Staphylococcus aureus from Milk and Dairy Products Sold in Some Local Markets of Mymensingh District of Bangladesh

This study was designed to isolate and characterize the Staphylococcus aureus from raw cow’s milk and some other dairy products sold in the local markets of Mymensingh district of Bangladesh by using conventional methods and molecular techniques. Raw cow’s milk, pasteurized milk, yogurt, roshmalai, cheese, lassi, matha, milk-shake, custard, faluda, pudding and borhani sampled from different retail shops and renowned restaurants of the local markets of Mymensingh. Out of 72 samples tested, all the samples revealed presence of Staphylococcus spp. and 57 isolates found coagulase positive S. aureus. The antimicrobial susceptibility pattern of the 57 pathogenic isolates was determined by using 10 commercially available antimicrobial drugs by disk diffusion assay. It exposed that majority of the isolates (79.16%) showed resistant to more than three antimicrobial agents. Among 57 isolates, 14 (24.56%) showed resistance against both methicillin and oxacillin, also intermediately resistant against vancomycin. Molecular detection of mecA and mecC gene in the 14 methicillin and oxacillin resistant isolates for the identification of methicillin resistant Staphylococcus aureus (MRSA) strains revealed 8 isolates (57%) from raw milk, yogurt, roshmalai, borhani and cheese to be positive for mecA gene while it was not detected in any other of the samples. None of the tested samples found mecC positive. Our findings revealed that the milk and dairy food products sold at local markets of Mymensingh are contaminated with multidrug resistant S. aureus elucidating a possible risk of MRSA infection which is alarming for both human and animal health.

Epidemiology of patients with MSSA versus MRSA infections of orthopedic implants: Retrospective study of 115 patients

Factors that predict the occurrence of a surgical site infection due to methicillin-resistant Staphylococcus aureus (MRSA) are not well known; however this information could be used to modify the recommended antimicrobial prophylaxis. We carried out a retrospective study of S. aureus infections on orthopedic implants to determine: (1) whether epidemiological factors can be identified that predict a MRSA infection, (2) the impact of these factors as evidenced by the odds ratio (OR). HypothesisRisk factors for a MRSA infection can be identified from a cohort of patients with S. aureus infections. Materials and methodsWe identified 244 patients who experienced a S. aureus surgical site infection (SSI) in 2011–2012 documented by intraoperative sample collection. Of these 244 patients, those who had a previous SSI (n=44), those with a SSI but no orthopedic implant (n=80) or those who had the infection more than 1-year after the initial surgery (n=5) were excluded. This resulted in 115 patients (53 arthroplasty, 62 bone fixation) being analyzed for this study. There were 24 MRSA infections and 91 MSSA infections. The following factors were evaluated in bivariate and multifactorial analysis: age, sex, type of device (prosthesis/bone fixation), predisposition (diabetes, obesity, kidney failure), and environmental factors (hospitalization in intensive care unit within past 5 years, nursing home stay). ResultsTwo factors were correlated with the occurrence of MRSA infections. (1) Nursing home patients had a higher rate of MRSA infections (67% vs. 18%, P=0.017) with an OR of 8.42 (95% CI: 1.06–66.43). (2) Patients who had undergone bone fixation had a lower rate of MRSA infections than patients who had undergone arthroplasty (13% vs. 30%, P=0.023), OR 0.11 (95% CI: 0.02–0.56). Although the sample size was too small to be statistically significant, all of the patients with kidney failure (n=4) had a MRSA infection. DiscussionSince these MRSA infection risk factors are easy to identify, the antimicrobial prophylaxis could be adapted in these specific patient groups.

Molecular analysis of methicillin-resistant Staphylococcus aureus dissemination among healthcare professionals and/or HIV patients from a tertiary hospital.

Methicillin-resistant Staphylococcus aureus (MRSA) is a nosocomial pathogen in community settings. MRSA colonized individuals may contribute to its dissemination; the risk of MRSA infection is increased in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) patients, although the prevalence of colonization in this group is not well established. The present study addressed this issue by characterizing MRSA isolates from HIV/AIDS patients and their healthcare providers (HCPs) to determine whether transmission occurred between these two populations. A total of 24 MRSA isolates from HIV-infected patients and five from HCPs were collected between August 2011 and May 2013. Susceptibility to currently available antimicrobials was determined. Epidemiological typing was carried out by pulsed-field gel electrophoresis, multilocus sequence typing, and Staphylococcus cassette chromosome (SCCmec) typing. The presence of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) and heterogeneous daptomycin-resistant Staphylococcus aureus (hDRSA) was confirmed by population analysis profile. Isolates characterized in this study were also compared to isolates from 2009 obtained from patients at the same hospital. A variety of lineages were found among patients, including ST5-SCCmecII and ST30-SCCmecIV. Two isolates were Panton-Valentine leukocidin-positive, and hVISA and hDRSA were detected. MRSA isolates from two HCPs were not related to those from HIV/AIDS patients, but clustered with archived MRSA from 2009 with no known relationship to the current study population. ST105-SCCmecII clones that colonized professionals in 2011 and 2012 were already circulating among patients in 2009, but there is no evidence that these clones spread to or between HIV/AIDS patients up to the 7th day of their hospitalization.

Risk of MRSA Infection in Patients with Intermittent versus Persistent MRSA Nares Colonization.

To determine the relative risk of invasive methicillin-resistant Staphylococcus aureus (MRSA) infection among non-colonized (NC) patients, intermittently colonized (IC) patients, and persistently colonized (PC) patients. Observational cohort study of patient data collected longitudinally over a 41-month period. Department of Veterans Affairs Eastern Colorado Healthcare System, a tertiary care medical center. Any patient who received ≥5 MRSA nasal swab tests between February 20, 2010, and July 26, 2013. In total, 3,872 patients met these criteria, 0 were excluded, 95% were male, 71% were white, and the mean age was 62.9 years on the date of study entry. Patients were divided into cohorts based on MRSA colonization status. Physicians reviewed medical records to identify invasive infection and were blinded to colonization status. Cox and Kaplan-Meier analyses were used to assess the relationship between colonization status and invasive infection. In total, 102 patients developed invasive MRSA infections, 16.3% of these were PC patients, 11.2% of these were IC patients, and 0.5% of these were NC patients. PC patients were at higher risk of invasive infection than NC patients (hazard ratio [HR] 36.8; 95% CI, 18.4-73.6; P<.001). IC patients were also at higher risk than NC patients (HR, 22.8; 95% CI, 13.3-39.3; P<.001). The difference in risk between PC and IC patients was not statistically significant (HR, 1.61; 95% CI, 0.94-2.78, P=.084). Alternate analysis methods confirmed these results. The risk of invasive MRSA infection is much higher among PC and IC patients, supporting routine clinical testing for colonization. However, this risk is similar among PC and IC patients, suggesting that distinguishing between the 2 colonization states may not be clinically important.

Duration of Colonization With Methicillin-Resistant Staphylococcus aureus: A Question With Many Answers

Duration of Colonization With Methicillin-Resistant Staphylococcus aureus: A Question With Many Answers

Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus colonization in HIV infection: a meta-analysis.

Human immunodeficiency virus (HIV)-infected individuals who are colonized with methicillin-resistant Staphylococcus aureus (MRSA) have increased risk for MRSA infection. We conducted a meta-analysis of published studies to estimate the prevalence of MRSA colonization in this population. We performed a systematic literature review and meta-analysis. The PubMed and Embase databases were searched and studies reporting prevalence of MRSA colonization among HIV-infected individuals were included. Among 7940 citations, 32 studies reporting data on 6558 HIV-infected individuals were considered eligible for our meta-analysis. We found that 6.9% (95% confidence interval [CI], 4.8-9.3) of individuals with HIV infection are MRSA carriers, with the corresponding figure across North American studies being 8.8% (95% CI, 6.0-12.2). History of hospitalization during the previous 12 months was associated with a 3.1 times higher risk of MRSA colonization (risk ratio [RR], 3.11 [95% CI, 1.62-5.98]). Previous or current incarceration was also associated with a higher risk for carriage (RR, 1.77 [95% CI, 1.26-2.48]). Current antiretroviral therapy or use of trimethoprim-sulfamethoxazole did not impact the risk of MRSA carriage (RR, 1.02 [95% CI, .64-1.63] and 1.45 [95% CI, .69-3.03], respectively). Extranasal screening increased the detection of MRSA colonization by at least 31.6% (95% CI, 15.8-50.0). The added yield from groin screening was 19.3% (95% CI, 11.5-28.5), from perirectal screening 18.5% (95% CI, 7.4-33.2), and from throat cultures 17.5% (95% CI, 12.0-24). Individuals with HIV infection constitute a highly vulnerable population for MRSA colonization, and prior exposure to hospital or incarceration are significant factors. Nasal screening alone will underestimate the rate of colonization by at least one-third.

Meta-Analysis of Methicillin-Resistant Staphylococcus aureus Colonization and Risk of Infection in Dialysis Patients

Patients undergoing dialysis are particularly vulnerable to methicillin-resistant Staphylococcus aureus (MRSA) infections. We performed a meta-analysis of published studies to estimate the prevalence of MRSA colonization in dialysis patients, time trends, and long-term risk of subsequent MRSA infections. Our search of the PubMed and Embase databases returned 5743 nonduplicate citations, from which we identified 38 relevant studies that included data on 5596 dialysis patients. The estimated prevalence of MRSA colonization was 6.2% (95% confidence interval [95% CI], 4.2% to 8.5%). The prevalence increased over time but remained stable after 2000. Stratification of patients according to dialysis modality and setting revealed that 7.2% (95% CI, 4.9% to 9.9%) of patients on hemodialysis were colonized with MRSA compared with 1.3% (95% CI, 0.5% to 2.4%) of patients on peritoneal dialysis (P=0.01), and that a statistically significant difference existed in the percentage of colonized inpatients and outpatients (14.2% [95% CI, 8.0% to 21.8%] versus 5.4% [95% CI, 3.5% to 7.7%], respectively; P=0.04). Notably, the risk of developing MRSA infections increased among colonized hemodialysis patients compared with noncolonized patients (relative risk, 11.5 [95% CI, 4.7 to 28.0]). The long-term (6-20 months) probability of developing a MRSA infection was 19% among colonized hemodialysis patients compared with only 2% among noncolonized patients. In summary, 6.2% of dialysis patients are MRSA colonized, and the average prevalence of colonization has remained stable since 2000. Colonization in hemodialysis patients is associated with increased risk of MRSA infection.